-1 tests included. The patch doesn't appear to include any new or modified tests.
Please justify why no new tests are needed for this patch.
Also please list what manual steps were performed to verify this patch.

+1 javac. The applied patch does not increase the total number of javac compiler warnings.

+1 javadoc. The applied patch does not increase the total number of javadoc warnings.

+1 checkstyle. The patch generated 0 code style errors.

+1 findbugs. The patch does not introduce any new Findbugs (version 2.0.3) warnings.

+1 release audit. The applied patch does not increase the total number of release audit warnings.

Tajo QA
added a comment - 20/Apr/15 23:21 -1 overall. Here are the results of testing the latest attachment
http://issues.apache.org/jira/secure/attachment/12726694/TAJO-1574.Hyun.150421.0.patch.txt
against master revision release-0.9.0-rc0-270-g2a5d912.
+1 @author. The patch does not contain any @author tags.
-1 tests included. The patch doesn't appear to include any new or modified tests.
Please justify why no new tests are needed for this patch.
Also please list what manual steps were performed to verify this patch.
+1 javac. The applied patch does not increase the total number of javac compiler warnings.
+1 javadoc. The applied patch does not increase the total number of javadoc warnings.
+1 checkstyle. The patch generated 0 code style errors.
+1 findbugs. The patch does not introduce any new Findbugs (version 2.0.3) warnings.
+1 release audit. The applied patch does not increase the total number of release audit warnings.
+1 core tests. The patch passed unit tests in tajo-algebra tajo-plan.
Test results: https://builds.apache.org/job/PreCommit-TAJO-Build/753//testReport/
Console output: https://builds.apache.org/job/PreCommit-TAJO-Build/753//console
This message is automatically generated.

ASF GitHub Bot
added a comment - 20/Apr/15 22:58 Github user dongjoon-hyun commented on the pull request:
https://github.com/apache/tajo/pull/548#issuecomment-94587626
Sure. The changed codes are in `tajo-algebra` and `tajo-plan`. I will add a testcase to cover both cases in somewhere.

ASF GitHub Bot
added a comment - 20/Apr/15 22:40 GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/tajo/pull/548
TAJO-1574 : Fix NPE on natural join
Please see the description in https://issues.apache.org/jira/browse/TAJO-1574 .
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/tajo TAJO-1574
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/tajo/pull/548.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #548
commit 86ac01d5d946bb540085f269eadb1860c73f033c
Author: Dongjoon Hyun <dongjoon@apache.org>
Date: 2015-04-20T22:38:04Z
TAJO-1574 : Fix NPE on natural join